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S. C. HOWELL.

l 'LITHARGB FURNAOE. No. 370,892. Patented-oct. 4, 1887.

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LITHARGB FURNACE.

Patented Oct. L1,y '1887.

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NA PETERS, PhuhrLilhugnPhsr, Washington, 0.6,

UNITED STATES 1 PATENT Erice.

SAMUEL c. EowELL, or EoSToN, MASSACHUSETTS, ASSrcNoE or EWE- -EIGJTTHSTo JAMES w. NEwELL AND JAS. w. NEwELL, TRUSTEE, or

SAME PLACE.

FURNACE.

SPECIFICATION forming part cf Letters Patent No. 370,892, dated October4, 1887.

Application filed February 3, 1886. Serial N0.190.'I19. (Nomozlcl.)

To all whom it may concern:

Be it known that I, SAMUEL C. ROWELL, of Boston, county of Suffolk, andState of Massachusetts, have invented an ImprovementinLitharge-Furnaces, of which the following description, in connectionwith the accompanying drawings, is a specification, like letters on thedrawings representing like parts.

This invention has for its object to provide a method whereby plumbicoxide or, as it is commercially known, litharge7 may be produced frommetallic lead more quickly and in a purer state than h as beenheretofore accomplished.

I have by experiment discovered that lithargeof pure quality may berapidly and econom1cally produced by placing the lead in a retortingfurnace or chamber the outside of which is heated to the requireddegree, the retorting-chamber being supplied by air preferably heatedand preferably supplied at the bottom of the Said chamber or in suchmanner as to pass upward through and over the molten lead, thus keepingthe said lead in agitation, the preferably-heated air forced into thesaid chamber thus agitating the lead,which results in exposing to theoxygen of the heated air a greater surface of lead than otherwise, thusmore thoroughly and rapidly oxidizing the lead.

In the practice of my invention I prefer to divide the process into twostepsz. e., first, heating the metallic lead in a retorting-chamber toor a little above its melting point, andl when raised to such heatforcing preferably heated atmospheric air over or through the moltenmass of metal,whereby the lead is converted into impure litharge, theimpurity of the litharge consisting chiefly of metallic lead, the impurelitharge appearing in the form of a dross, which, removed from theretortingchamber, is, secondly, submitted in a calcining-chamber,maintained at a heat preferably higher than that at which theretorting-chamber is. maintained, to the influence of air preferablymore highly heated than the air in the retorting-chamber in which thelead was first placed.

My invention consists in a furnace having certain novelties ofconstruction, as will be hereinafter described, and also in a new methodo f forming litharge.

Figure 1 is a vertical section of a furnace with which to practice myinvention, the section being taken on the irregular line am, Fig. 3, andalso showing the chimney in Section. Fig. 2 is a transverse section ofFig. l on line ai x; Fig. 3, a transverse section of Fig. l on line y y,with the chimney removed; and Fig. 4, a side elevation of Fig. l,partially broken out to show the hot-air tuyere.

Referring to the drawings, Arepresents the brick-work of a furnaceprovided with a chimney or due, A', herein shown as extended to thebottom ofY Said furnace. The interior of the furnace referred to isdivided centrally by a wall, a, supporting one end of the arched roof a.of a combustion -chamber, a2, containing the fire-grate as, upon whichis placed fuel, preferably coke, which furnishes the heat to melt thelead, saidheat being directed through said furnace in a manner to behereinafter fullyvdescribed and designated by full arrows. The centralwall, a, also supports one end of the arched roof ai, forming part of aflue, c2.

The brick-work c, suitably laid, forms the bottom of acalcining-chamber, a5, and also tne roof of a receiving-chamber, al,said chambers being connected by a chute, a8, preferably located nearone end of said chambers, as shown in Fig. 3.

Above the arched roofs a a4, referred to, and which constitute the topof the greater part of the furnace, (see Fig. 4,) the walls of thefurnace are extended upward to form the main or retorting chamber b.

The bottom of the retorting-chamber b is herein shown as composed of ametal plate, b,'

part of the plate b', the tuyere communicating with the passage b2 bythe port 56.

The plate e, preferably of metal, constitutes the roof of thecalcining-chamber a5, and also the floor or under part of the flue c.

The upper portion of the plate b', and upon which the lead is placed, isherein shown as provided with perforations c for thc passage of air,which is forced up through the molten lead, said lead being melted byheat which cscapes'from the fire-chamber a2 through passage c', the uec2, thence through the fluepassages c e5, as indicated by the full-linearrows, the latter passage being between the arched roofs a a4 and theplate b', and thence through the passage e6 into the chimney or ilue A.The air by which the molten lead is oxidized is preferably forced by anair-pump (not shown) through a series of connected pipes located in theiirechamber ai, and shown in plan view, Fig. 3, the said pipes beingherein shown as of arch shape and erected upon and communicating withboxes d d, having parti-` tions at suitable intervals, to compel the airentering the boxes to traverse the arched pipes one after the other,after the manner of a coil.

The boxes d d2 are supported upon the brick-work, as shown in Figs. land 3, and extend throughout the length of the chamber al. The boxesreferred to and their attached arched pipes are so divided at or nearthe center of the length of the chamber a2 as to form two batteries, oneof which, as hereinafter described, is made to receive atmospheric airand supply it in more or less heated condition to the retorting-chamberb, the other battery furnishing air more or less heated to thecalcining-chamber a5, the direction of tlow of the heated air beingdesignated by the dotted arrows 2 and 3, the arrow 2 showing the courseof the air which enters the chamber b and the arrow 8 that which entersthe chamber a5. The pipe f, which connects one of the said batterieswith the tuyere I1, is shown partially in dotted lines in Figs. l and 2,and completely in full and dotted lines, Fig. 4. From the tuyere b5 theheated air passes through the port b, passage b2, and perforations c upthrough the molten lead, said lead being oxidized by said air, chieiiy,to litharge. The litharge, being ofV less specific gravity than metalliclead, rises to the surface of the molten mass. As the litharge isformed, it is raked or scraped up onto'the inclined part of the plateb', and when a sufcient quantity has thus been accumulated a cover, g,of a chute or hopper, g', extended through the arch a* and leading intothe calcining-chamber a5, (see dotted lines, Fig. 1,) is raised, and thelitharge and its impurities, chiefly metallic lead, are raked into thehopper or chute g', through which it fallsinto the chamber a5, themetallic lead being acquired by the scraping of the litharge up on theinclined plate b. Access to the chamber b is obtained through a door,g2, in the side of the furnace. The litharge and its impurities in thecalcining-chamber a5 are still further subjected to the oxidizinginiiuence of heated air, the cover g being replaced upon Athe chute g.

The heated air which passes through the calcining-chamb'er c5 is forcedtherein from the battery through a compartment, h, in the box d', whichcompartment is connected by p ipe h5 (see Fig. l) with a box or channel,h", said channel extending the length of the chamber a5 and beingprovided with a series of ports or openings, hl, (see Figs. l and 3,)which are connected with the calcining-chamber a", the air being forcedinto the battery from the front side of the furnace, as indicated byarrow 3, preferably by a fan. (Not shown.) The temperature of thecalcining-chamber will preferably be somewhat higher than that of therctorting-ehamber b, it being preferably between the fusing andvolatilizing points of lead. rlhe excess of heated air in thecalcining-chamber a" finds an exit therefrom through the passages k,made at intervals in the wall of the furnace and throughout the lengthof said chamber, said passages being made continuous and preferablyconnected to the flue c. From the flue c the hot air passes through thepassages c" and c5, and thence to the chimney A by the passage c, thehot air on its way to the chimney imparting heat to the metal plate b',thus assisting in the melting of the lead supported in the concavedportion of said plate. The products of combustion passingfrom thecombustion-chamber al through the line-passage e and into the chamber c2heat the metal shield al, which radiates its heat into the chamber a5and down upon the litharge, thereby raising-the temperature of saidchamber. The impurities of the metallic lead which may be volatilizedand the excess of air in the chamber b are carried off by the liuc m.The litharge is permitted to remain in the chamber ed'l until it hasacquired the desired color or tone, when it is scraped or raked throughthe chute a into the receivingchamber al, from whence it is taken readyfor grinding.

Instead of dividing the plate b and perforating the upper portion ofsaid plate, I may employ a false bottom, which would rest upon the plateb', and would be provided with perforations, the false bottom formingpart of the tuyere b5.

It will be herein noticed that the products of combustion are preventedfrom coming in contact with the metallic lead, thereby preventing theformation of comparatively large quantities of carbonate of lead,whichis formed when the products of combustion come in contact with the lead,and which exists as an impurity in litharge thus made.

I have herein shown a mechanism well adapted to economically heat airand introduce it into the retorting and calcining chambers, and I havealso, as so far described, referred to the form of heat as coal or cokeupon the grate; but I wish it to be understood that I do not desire tolimit my invention to the employment of the exact means herein shown forheating the air to be discharged into the said chambers, for insteadthereof I may employ any usual means or method of heating air IOO to beintroduced into furnaces for industrial uses, and so, also, I may use,as the generator of heat, gas, oil, or any other usual fuel instead ofcoke, the use of gas or oil as the fuel necessitating the applicationtothe furnace of usual means for burning the same.

I am aware that prior to my invention litharge has been formed byforcing air through a mass of melted lead ore; but litharge produced inthis manner is of a poorer quality and does not have the desired tone orcolor, which latter is of vital importance, and which is obtained. by mein the calcining-chamber,

1. In a furnace for the manufacture of litharge, the combustion-chamber,the retortingchamber to contain metallic lead and having a hollow bottomperforated to permit heated air to bc forced up through the lead, andpas sages connecting said combustion-chamber with the chimney and madeto cause the products of combustion to pass beneath and in chamberlocated below and communicating with the retorting-chamber and with abattery of pipes communicating with the calciuing-chamber, to operatesubstantially as described.

3. Thatimprovementin the process of manufacturing litharge from metalliclead which consists, rst, in forcing air through the mass of lead in amolten state in one chamber, and, second, in transferring the impurelitharge thus formed to a second chamber, and therein subjecting saidimpure litharge to the action of heated air in said second chamber,substantially as described.

4. The improvement in the art or method of manufacturing litharge, whichconsists in subjecting melted lead to the action of heated air in aretortiug chamber and thereafter subjectingthe dross or impure lithargethus formed to the action of heated air in a calciuing-chambermaintained at a higher temperature than the retorting-chamber,substantially as described.

In testimony whereof I have signed my name 55 to this specification inthe presence of two subscribing witnesses.

SAMUEL C. HOWELL.

Witnesses:

G. W. GREGORY, F. L. EMERY.

